1. Field of the Invention
The present invention relates to a device for automatically detecting picture degradation that detects local picture or video degradation caused by transmission failure in picture or video transmission.
2. Description of the Related Art
One of conventional technologies for detecting local picture degradation caused by transmission failure in the video transmission is disclosed in Japanese Unexamined Patent Publication No. 2002-77949 applied by the present applicant.
This conventional technology is such that in a system having a plurality of transmission processing units connected in series to a transmission line, a feature quantity of a picture is extracted at a predetermined point on the video transmission circuit and is transmitted through a low bit-rate (data) circuit such as telephone network and LAN to a central monitoring apparatus and the central monitoring apparatus compares the feature quantity to evaluate transmitted picture quality.
However, the feature quantity obtained by the conventional technology is the average value, the variance and the like of brightness in the field of a received picture. Hence, in a case where picture quality degradation is caused by the transmission failure, it can be determined that the degree of degradation of a picture (frame) is high but it is impossible to specify a portion where the picture quality degradation is specifically caused.
Moreover, in a case where a degraded region in a frame is caused in an extremely small range, it is expected in some cases that even if the average value of degree of the picture quality degradation in the frame is obtained, the average value remains a high value and hence it cannot be determined that picture quality degradation is caused in the region. For this reason, there is required a method of specifying a portion in the frame where picture quality degradation is caused.